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<b>DbEnv::txn_recover</b>
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<tt>
<b><pre>
#include &lt;db_cxx.h&gt;
<p>
int
DbEnv::txn_recover(DB_PREPLIST preplist[],
    long count, long *retp, u_int32_t flags);
</pre></b>
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<b>Description: DbEnv::txn_recover</b>
<p>Database environment recovery restores transactions that were prepared,
but not yet resolved at the time of the system shut down or crash, to
their state prior to the shut down or crash, including any locks
previously held.  The DbEnv::txn_recover method returns a list of those
prepared transactions.</p>
<p>The DbEnv::txn_recover method should only be called after the environment has
been recovered.</p>
<p>Multiple threads of control may call DbEnv::txn_recover, but only one
thread of control may resolve each returned transaction, that is, only
one thread of control may call <a href="../api_cxx/txn_commit.html">DbTxn::commit</a> or <a href="../api_cxx/txn_abort.html">DbTxn::abort</a>
on each returned transaction.  Callers of DbEnv::txn_recover must call
<a href="../api_cxx/txn_discard.html">DbTxn::discard</a> to discard each transaction they do not resolve.</p>
<p>On return from DbEnv::txn_recover, the <b>preplist</b> parameter will
be filled in with a list of transactions that must be resolved by the
application (committed, aborted or discarded).  The <b>preplist</b>
parameter is a structure of type DB_PREPLIST; the following DB_PREPLIST
fields will be filled in:</p>
<br>
<b>DB_TXN * txn;</b><ul compact><li>The transaction handle for the transaction.</ul>
<b>u_int8_t gid[DB_XIDDATASIZE];</b><ul compact><li>The global transaction ID for the transaction.  The global transaction
ID is the one specified when the transaction was prepared.  The
application is responsible for ensuring uniqueness among global
transaction IDs.</ul>
<br>
<p>The DbEnv::txn_recover method
either returns a non-zero error value
or throws an exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</p>
<b>Parameters</b> <br>
 <b>count</b><ul compact><li>The <b>count</b> parameter specifies the number of available entries
in the passed-in <b>preplist</b> array.  The <b>retp</b> parameter
returns the number of entries DbEnv::txn_recover has filled in, in the
array.</ul>
 <b>flags</b><ul compact><li>The <b>flags</b> parameter must be set to one of the following values:
<br>
<b><a name="DB_FIRST">DB_FIRST</a></b><ul compact><li>Begin returning a list of prepared, but not yet resolved transactions.
Specifying this flag begins a new pass over all prepared, but not yet
completed transactions, regardless of whether they have already been returned
in previous calls to DbEnv::txn_recover.
Calls to DbEnv::txn_recover from different threads of control should not
be intermixed in the same environment.</ul>
<b><a name="DB_NEXT">DB_NEXT</a></b><ul compact><li>Continue returning a list of prepared, but not yet resolved transactions,
starting where the last call to DbEnv::txn_recover left off.</ul>
<br></ul>
 <b>preplist</b><ul compact><li>The <b>preplist</b> parameter references memory into which
 the list of transactions to be resolved by the application is copied.</ul> 
<br>
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<br><b>Class</b>
<a href="../api_cxx/env_class.html">DbEnv</a>, <a href="../api_cxx/txn_class.html">DbTxn</a>
<br><b>See Also</b>
<a href="../api_cxx/txn_list.html">Transaction Subsystem and Related Methods</a>
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